View Full Version : tj wrangler experts?
Daughters tj just took a dump.
She drove to the dairy queen and lost power, said it was hard to steer.
I'm here and it cranks, but won't carch & fire.
97 4.0 auto.
Fuel pump,
Computer?
I don't know jeeps much, but this thing is simple.
Thoughts?
dogbreath650
11-03-2016, 18:21
gas?
Aardvark
11-03-2016, 18:28
"cranks but won't catch" = may be a bad battery cell. I'm thinking if it lost power, it's electrical and not fuel pump related. I'd start with the battery, check for good ground from battery to engine block (corrosion on cables will play havoc w/the TJ).
SideShow Bob
11-03-2016, 18:31
Check for spark at the plugs, could be the crank angle sensor, or other ignition components.
Maybe the muffler bearings or blinker fluid?
[Dunno]
Fuel pump, jeeps notorious for it. Replaced the one in my xj twice
Is it getting fuel, when you turn the key to the on position, can you hear the fuel pump in the tank for a few seconds. Is there a test port on the fuel rail? If you have fuel pressure, check spark.
May be a crank sensor as well. Check fuel and spark first.
"cranks but won't catch" = may be a bad battery cell. I'm thinking if it lost power, it's electrical and not fuel pump related. I'd start with the battery, check for good ground from battery to engine block (corrosion on cables will play havoc w/the TJ).
A hard steering condition is either the engine quit running, or the belt broke. Based on "crank but won't catch/start, indicates the engine won't run. A bad cell in a battery will reduce overall voltage and battery output, but won't cause and engine to crank/no start. Spark will be weakened until the alternator spins fast enough with the engine running to take over.
SideShow Bob
11-03-2016, 20:33
Check fuel and spark first.
Best advise so far. Start with the basics first.
Got it towed home and in the garage. That was half the battle.
Battery connections have a little corrosion, I'll get those cleaned and test/charge the battery.
Thanks for that blinker fluid tip Ray, I'll look into that...
Does have spark, that's good. All belts are in place.
Can't hear the fuel pump, but I only hear half what most of you guys hear... I'll be looking more into it tomorrow.
Thanks for the tips.
Ask her if she recently filled the tank with fuel. I've heard that fuel pumps like to go on a fresh, full tank. That certainly happened to me with my Cavalier.
newracer
11-03-2016, 23:36
There is a Schrader valve on the fuel rail that you can use to check pressure.
SideShow Bob
11-04-2016, 12:49
Since you have spark, Try dribbling a few drops of gasoline down the intake while cranking it over to see if it will fire up.
and I do mean a small amount of fuel, as in drops.
I don't know if jeeps of that year have a power cut off switch to the fuel pump that kills power after an impact, but I had a Ford of that vintage that did. It started tripping on bad potholes or bumps and needed manually reset.
That cost me a fuel pump replacement from a rip off mechanic before I figured it out.
fportmen45
11-04-2016, 13:32
Cam position sensor.
Spray a bit of brake cleaner in the air intake while cranking. If it will run with that , it means you aren't getting fuel. No fuel probably means the pump had failed. I would recommend replacing pump and filter at the same time and go get a mopar pump.
Spray a bit of brake cleaner in the air intake while cranking. If it will run with that , it means you aren't getting fuel. No fuel probably means the pump had failed. I would recommend replacing pump and filter at the same time and go get a mopar pump.
If he's going to use brake cleaner he might make sure it's the chlorinated type. I think the non-chlorinated stuff isn't flammable.
I always preferred carburetor cleaner myself.
Spray a bit of brake cleaner in the air intake while cranking. If it will run with that , it means you aren't getting fuel. No fuel probably means the pump had failed. I would recommend replacing pump and filter at the same time and go get a mopar pump.
If he's going to use brake cleaner he might make sure it's the chlorinated type. I think the non-chlorinated stuff isn't flammable.
I always preferred carburetor cleaner myself.
Why not Starting Fluid?
Brake cleaner is much cheaper. But any of them should work just fine.
All brake parts cleaner is flammable, it's mostly acetone. Windshield washer fluid is typically 50/50.methanol and water, very flammable. You could use that in a pinch too. Easiest way to see if there's fuel pressure is to push the schrader valve on the fuel pressure test port. It's on the fuel rail near the front according to Google.
Brake cleaner is much cheaper. But any of them should work just fine.
Noted. Thanks
Not all brake clever is flammable look for the don't die this is flammable warnings on the side of your want it to be.
3m brake cleaner is the best I have come across for cleaning jobs and amazingly flammable we use it if we are out of ether at the shop during cold weather spurts when trucks are gelled
and windshield wiper fluid is great for water meth injection systems
I have never seen non flammable brake cleaner. News to me. And yes, 3M is the best.
Just use a small flat head, depress the Schrader valve in the fuel supply line, if nothing shoots out you likely have a dead pump. Obviously keep your face out of the way, Id use a shop towel to keep it from spraying everywhere, you'll know if there's pressure.
Ya that's also how I check my tire pressure. Just push in on the valve and if air comes out I'm good to go.
Fantastic tips I appreciate them.
I didn't touch the Jeep until this morning, went out and it fired right up. I didn't do anything in the mean time. We got it in the garage thursday night, never touched it friday and this morn it fired. I turned it on and off half the day, let it run for a long time, checked all the connections, cleaned some, drove it around the block, parked and it always fired right back up. Intermittant fuel pump, or crank sensor???
Kind of at a loss. We'll see if anything changes tomorrow and then I may give up and take it in to the shop. Diagnosing these issues is a pain.
Just use a small flat head, depress the Schrader valve in the fuel supply line, if nothing shoots out you likely have a dead pump. Obviously keep your face out of the way, Id use a shop towel to keep it from spraying everywhere, you'll know if there's pressure.
This post is hilarious based on graves avatar.
I say still the fuel pump. It's a cheap fix . Do it before it dies somewhere else
I'm not familiar with Jeeps but I've had several GM vehicles that had ignition modules that would quit working when they got hot. If you let the vehicle sit and cool off for a while it would fire right back up and act normal.
Might add that to your ever growing list of things to check.
He has never lost spark, so an ignition module is ruled out. Fuel pump relay maybe. I have seen fuel pumps be intermittent, but not for long. And they don't put out enough pressure or volume when testing them.
He has never lost spark
Oh. I must have missed that part. My bad.
SideShow Bob
11-06-2016, 11:20
But he had spark after it had sat awhile & after being towed home.....
So, it is anyone's guess as to what is going out.
he'll have to wait and drive it until the offending part gives up the ghost for good.
newracer
11-06-2016, 12:20
Have you checked for any codes?
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Nothing to follow up on here. Never found an issue, and I started letting the daughter drive the jeep again. So far, with no issues.
I took it in to my favorite shop, I was told there were no codes, and they couldn't find any issue, so we're playing Russian Roulette with the TJ.
Thanks for all your tips and thoughts tho, I appreciate it.
All brake parts cleaner is flammable, it's mostly acetone.
https://lh3.googleusercontent.com/YYwUfqxTVZPe3HH1AbrWFMjyDnTW0T8AJ27DvcFRcybpxkNQAO F75YGgMxaGpYE02zp2SWth49gvblG-vy0j7wCnmq76AIJIiC6cmQTPsiSu6bp_gnIHd5C8espCpcHw_3 9LWrtgJ17R1LWcfWFguS22ZvGHMJAJlUyZzwaOF_2CN29GRLZx qTPqJkKgetl7smn3HT4jl-1MvpNqmBr1eNLQf7fucpp8oIYhEvWXAQNhXS6fpbSTD2fMwWgu LvWPLKj8-nRdUQb1QJJHC5VhZorI2089YPWMQwv85Lj3OswuDLpA7cvlupe 5wEnohgsIt27X1COY9P9wQklVSDeU72GxsA7cSjwArzutWWr_Z E7xDNi62HeJIUhjceJefGTRU1KKgpkTQPYwgzn1fQ3VO8uJHGd ExNmq-yhrcNOAUtav9u3qHWFNOcmE1fK8iP_DmRT-mRWBCMQK8jkxkBSI2IPy6wBKC7witqfAis9780bR7onTWObZC3 73uj8YfgaVY5uxY0Po8sZV721CcJirLVRWv4Ihs7NVe1_LkCk7 qsee9KZAdIKOQ6Md1ARkXRPAphKFG-mQ_xYdxVPTce-LuGa7vmtJATSw4RRgEzDIkMPZiJekYA=w1689-h950-no
I would take a close look at the connections on the battery as well.
It was an intermittant fuel pump, took a crap right in front of the house yesterday, thank God for that small miracle. Same deal as before, fired right up again but it finally sputtered and died when I was messing with it.
So to those who called the fuel pump, you were right.
Glad you got it fixed I was worried it would die on you somewhere not at home . Hard one since they go out then start working again intermittently.
SouthPaw
11-24-2016, 20:20
Cam position sensor.
This would my starting point. 4.0L are known for these.
This would my starting point. 4.0L are known for these.
Problem was already figured out, it was a fuel pump. And checking fuel is usually the first place to start on a no-start diagnosis.
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